In a starter combustor of a pressurized fluidized bed combined cycle power system, disorder of a flame detecting device due to ash accumulation is prevented. A fuel nozzle (33) of the starter combustor is provided so as to be directed to an inner cylinder (32) and a pipe (38) of a fitting pipe (36), which is connected to the inner cylinder (32). A valve body (1), having a valve body passage (1a), is provided so as to be connected to one end of the fitting pipe (36) and a valve component (3). The valve component (3) has a recess portion 3a and is connected to a shaft (1a) . When the combustor is started, the shaft (2), which is engaged rotatably with shaft fitting portion (3a') of the valve component (3) and is in threaded engagement with a threaded portion of the valve body (1), is moved by handle (4) so that the valve component is moved and the passage (1a) is opened. While the combustor is stopped, the passage (1a) is closed by the valve component (3). In ordinary operation time, ash is collected in the recess portion (3a) of the valve component (3), and therefore ash does not accumulate on a glass plate (37) and disorder of the flame detecting device due to ash accumulation does not occur.